1. Field of the Invention
This invention relates generally to window air filters. More particularly, the present invention relates to a filter window adapter unit for use with a main split-sash window of school buses, passenger coach vehicles, and the like.
2. Description of the Prior Art
As is generally known, school buses are used by state and local school districts for transporting children safely and conveniently between their homes and classrooms. These school buses are typically provided with windows of the type referred to generally as “split-sash” windows. The split-sash window design includes two panes of glass consisting of an upper pane and a lower pane defining the window. Each piece of glass is usually held by a frame disposed around its perimeter. The lower pane is fixed-in-place, and the upper pane is allowed to move downwardly so as to open the window and move upwardly so as to close the window. The purpose of permitting the opening of the window is to allow for ventilation in which fresh outside air flows through the window and into the interior of the bus.
However, these school buses are usually powered by a diesel engine. Unfortunately, the diesel-powered school buses emit very small soot particles and toxic gases that pose a significant health problem to the children. When inhaled, the diesel exhaust can aggravate allergies, trigger asthma attacks and cause serious respiratory illnesses, such as bronchial or pulmonary troubles. Heretofore, the technological steps taken to make the school buses a healthier place for the children have thus far only involved the retro-fitting of the school buses with a diesel oxidation catalyst. The diesel oxidation catalyst is used merely to control the emission of the diesel fumes coming directly from engines thereof. This present solution does not address the problem of pollutants entering into the school buses through the opened windows from the outside environment.
Given the fact that more often than not the budgets of state and local educational departments are stretched to the limit, any available assets on hand for modifying the school buses so as to filter the soot particles and toxic gases from the diesel engines must be used to their maximum potential. Accordingly, what is needed is a filter window adapter unit for school bus windows which is of a simplified construction, relatively low in cost, and can be easily installed or retro-fitted over the existing main bus windows.
A prior art search directed to the subject matter of this application in the U.S. Patent and Trademark Office revealed the following Letters Patent and application:                U.S. Pat. No. 1,402,101 U.S. Pat. No. 6,279,266        U.S. Pat. No. 2,639,004 U.S. Pat. No. 6,463,983        U.S. Pat. No. 3,826,182 U.S. Pat. No. 6,471,137        U.S. Pat. No. 4,651,797 U.S. Pat. No. 6,499,527        
In addition to the above issued prior art patents, there were also found Patent Application Publication Nos. 2003/0213564 dated Nov. 20, 2003 and 2004/0065029 dated Apr. 8, 2004.
In U.S. Pat. No. 3,826,182 to Narava issued on Jul. 30, 1974, there is disclosed a window air filter which is mounted between a top sash of an upper window and a top window frame part. The filter medium of the air filter unit is contained within a housing which includes a mesh covering. The housing also includes a pair of channels, one being located at the top and the other one being located at the bottom of the air filter unit. End sleeves are slid over the respective channels. The filtering material is comprised of a charcoal impregnated material or charcoal granules.
In Published Patent Application No. 2004/0065029 to Morris dated Apr. 8, 2004, there is taught a removable portable window filter which fits inside a partially opened window or partially opened sliding glass door for preventing dirt and dust from entering a room by the outside air flowing around. The filter material is attached between two narrow parallel metal bars. The air filter is installed in the bottom opening of the window.
In U.S. Pat. No. 2,639,004 to McIntyre issued on May 19, 1953, there is taught window air filters each being mounted to a corresponding frame-like structure. Retainers are used to slidably secure the frames together. Two of the retainers are secured to the frame by a screw passing through a slot, which permits the retainers to have a sliding movement toward or away from each other.
U.S. Pat. No. 1,402,101 issued on Jan. 3, 1922 to Smith discloses a window frame in which is mounted a lower sash B and an upper sash C slidable in vertical planes. The lower sash B is shown in FIG. 1 to be partially raised and a ventilator frame D is inserted in the window frame under the bottom rail 1 of the lower sash B.
The remaining patents, listed above but not specifically discussed, are deemed to be only of general interest and show the state of the art in window screens and air filters installed in a window opening for filtering the air passing therethrough and preventing dust and dirt from blowing into the interior of a room.
None of the prior art discussed above disclosed a filter window adapter unit like that of the present invention which includes a mounting frame adapted to be installed over a main split-sash window of school buses and an outer sash with an air filter being movable so as to cover a main window opening when the main split-sash window is opened.